1. Field of the Invention
The invention relates to a safety device for a fluid transmission.
Such devices are suitable for limiting the pressure in a fluid transmission, in which respect the device protects parts of the fluid transmission as well as for example an energy converter connected to the fluid transmission or a load. A device of that kind can also be used for monitoring the volume flow in a fluid transmission.
2. Description of the Prior Art
The publication CC1N7651D from Landis and Gyr discloses a fluid transmission for setting a gas valve for a burner. The fluid transmission (in the edition of the publication dated August 1995, page 2) has a safety device including an axially displaceable hollow cylinder. The ends of the hollow cylinder are of such a configuration and are so arranged in the transmission that a respective throttle location for the hydraulic oil movable by a pump is operative on each of both sides. In dependence on the pressure conditions in the fluid the hollow cylinder is displaceable against a spring force, in which case the opening of one of the two throttle locations is variable and a return passage for the fluid can be fed through that throttle location. That safety device involves a high level of expenditure in terms of achieving the necessary close production tolerances and also requires relatively costly sealing elements. The necessary expenditure is very high in particular if the fluid transmission is to be designed for a relatively great temperature range.
The object of the present invention is to provide an inexpensive safety device which can be used reliably in a relatively wide temperature range.
In accordance with the present invention, there is provided a safety device for a fluid transmission comprising an energy converter and a consumer connected by way of a feed passage to the energy converter, wherein a pressure can be produced by the energy converter in a chamber of the consumer,
the safety device comprising:
a diaphragm which is arranged deflectably in the feed passage and which has at least one through opening for the fluid to pass therethrough, and
a return passage for the fluid to return from the chamber of the consumer, wherein the return passage is of such a configuration and arrangement that it can be opened and closed by deflection of the diaphragm, and
wherein the configuration of the diaphragm is such that when the fluid flow in the feed passage falls below a given value the return passage is opened.
Advantageous aspects of the invention are set forth in the dependent claims.